The floods that caused widespread loss to lives and property across Kerala in August have triggered alarming changes in soil quality, posing a threat to crop production, a study conducted by scientists at the Central Tuber Crops Research Institute (CTCRI) here has found.
The scientists who carried out a detailed survey of soil and sediment samples collected from the flood-hit areas reported fundamental changes in soil chemistry and structure and the microbial ecosystem. “We found wide variations in the soil pH in flood-hit areas,” says G. Byju, Principal Scientist, Soil Science.
A total of 178 samples were collected from all districts and analysed at the CTCRI laboratory. Soil pH of below 3.5, indicating abnormally high acidity, was reported from a sandy deposit in Vijayapuram grama panchayat in Kottayam district. The organic carbon content of the samples studied ranged from 0.06 to 4.55% and a very high value of 4.55% was recorded in a sample collected from Kasaragod district.
Analysis of major, secondary and micronutrients indicated changes in soil chemistry. In one of the samples collected from Neyyattinkara municipality, the available phosphorus content was to the tune of 755.87 kg a hectare, which is extremely toxic for crop cultivation. High levels of potassium, calcium and magnesium were detected in samples collected.
Micronutrients
Studies on micronutrients also showed very wide variation with one of the deposits from Pulimukku in Pathanamthitta district registering toxic level of iron content to the tune of 1,539.50 ppm. Dr. Byju said the study had revealed differences in soil composition and structure in flood-hit areas, with the potential to affect water infiltration, root growth, soil erosion, biological activities and nutrient cycling.
The study also found major changes in microbial population and structure with some areas registering abnormally high bacterial and fungal population. “Disturbance caused to the microbial ecosystem cannot be easily reversed through intervention as in the case of chemical changes,” points out Dr. Byju.
The scientistsstressed the need for site-specific crop management to address the changes at the micro level.
